Sizing compositions for textile yarns



United States Patent a.

Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed June 19, 1959, Ser. No. 821,365 4 Claims. (Cl. 117-1395) This invention relates to the sizing of textile yarns, more particularly ester yarns made of cellulose acetate or of linear polyesters. The linear polyesters of which the yarns may be made are the highly polymeric linear esters obtained by heating a glycol with an aromatic dibasic acid or its anhydride or with a mixture of an aromatic dibasic acid or its anhydride and an aliphatic dibasic acid or its anhydride under conditions which yield the esters in a highly polymerized condition. The manufacture of these linear polyesters, and the spinning of filaments therefrom, are described in the prior art, and form no part of our invention. Cellulose acetate yarns are, of course, well known in the art.

When cellulose acetate or linear polyesters are to be used in the form of multifilament yarns in the fabrication of textile materials, it is necessary before the weaving process to treat the warp yarn with a size which adheres to and binds the several filaments together, thus strengthening them and rendering them more resistant to abrasion during weaving operations, and which can subsequently be readily removed from the yarns by scouring. It is of especial importance that the sizing material impart a high degree of abrasion resistance to the yarn during the weaving operation. Abrasion tends to sever the yarns and to produce end breaks. This, of course, lowers the quality of the final woven product.

Various water-soluble high-molecular weight materials have been suggested as sizes for yarns. These include gelatin, Sodium Stymer (the sodium salt of a 50/50 maleic anhydride-styrene copolymer), sodium polyacrylate, polyvinyl alcohol, etc. Some of these materials, however, are not compatible with ester yarns, and thus do not form a protective coating or film on them; others coat the yarn but do not import more than a slight degree of abrasion resistance to it.

We have discovered that the water-soluble sodium salts of copolymers of N-lower alkyl acrylamides or N- lower alkyl methacry-lamides with polymeriza'ble unsaturated aliphatic acids are excellent sizes for cellulose acetate yarns and linear polyester yarns, imparting to them high weaving elliciency and excellent abrasion resistance, and that these sizes can be readily removed from the woven textile fabric by scouring. The following N-lower alkyl acrylamides and methacrylamides are among those which can be used in making these copolymers: N-isopropylacrylamide; N,N-dimethyl acrylamide; N-methyl methacrylamide; and N-isopropylmethacrylamide. N-isopropylacrylamide is an especially useful N-lower alkyl acrylamide. The following polymeriz-' able unsaturated aliphatic acids can be used as co-monomers with any of the aforementioned N-lower alkyl acrylamides or N-lower alkyl methacrylamides: acrylic acid, methacrylic acid, itaconic acid and crotonic acid. Acrylic acid is especially useful as a co-monomer. From 5% to 20% by weight of the acidic component may be used. A particularly useful composition comprises the sodium salt of the copolymer of 9 parts by weight of N-isopropylacrylamide and 1 part by weight of acrylic acid. The related polymers, sodium polyacrylate and unsubstituted polyacrylamides, 0n the other hand, are poor sizes for Patented July 18, 1961 cellulose acetate yarns and linear polyester yarns, and do not impart any unusually high abrasion resistance to them.

The copolymer of N-isopropyl acrylamide and acrylic acid may be prepared as follows:

Example 1. -540 parts of N-isopropylacrylamide and 60 parts of acrylic acid are dissolved in 11,400 parts of oxygen-free deionized water in a closed reaction vessel at 25 C. The apparatus is subjected to high vacuum for 30 minutes, and then to a slight positive pressure of nitrogen. 0.6 part of potassium persulfate and 0.6 part of potassium metabisultite are added and the reaction mixture is stirred; the temperature is held at 25 C. The reaction is essentially complete in 2 hours. The inherent viscosity of the product is about 3.5.

Example 2.--The sodium salt of the copolymer whose preparation is described in Example 1 may be prepared as follows: A sodium hydroxide solution is prepared by dissolving 33.3 parts of NaOH in 200 parts of water and cooling to room temperature. This solution is added to the copolymer until a pH of 7.0 is obtained. The aqueous solution of the sodium salt has a higher viscosity than an equivalent concentration of the free copolymer.

The use of this material in the sizing of yarns is illustrated by the following examples. Example 3.A polyester yarn composed of poly ethylene ter ephthalate is sized with a solution containing 5% of the neutral sodium salt whose preparation is described in Example 2. The size is applied by passing the yarn in warp form over a roller dipping in the solution and revolving at a constant rate. The sized material is dried and cured in the usual manner. A well-sized yarn is obtained.

Example 4.-Cellulose acetate yarn is drawn through a constant temperature size bath containing a 5% solution of the neutral sodium salt whose preparation is described in Example 2. The sized yarn is dried on a series of rotating heated cylinders and is taken up on a loom beam or other suitable device. After a period of curing under standard conditions of temperature and humidity, the state of bondedness between the protective size and the yarn filaments is determined by means of a :Duplan abrasion-resistance testing machine. A high Duplan value is indicative of a good size.

Example 5.-570 parts of N,N-dimethylacrylamide and 30 parts of itaconic acid were dissolved in 11,400 parts of oxygen-free water in a closed reaction vessel at 25 C. The polymerization was carried out as described in Example 1. The sodium salt was prepared as described in Example 2. A polyester warp similar to that described in Example 3 and a cellulose ester warp similar to that described in Example 4 were passed through this solution. A well-sized yarn was obtained in both instances.

Example 6.5l0 parts of N-isopropylmethacrylamide and parts of methacrylic acid were dissolved in 11,400 parts of oxygen-free water in a closed reaction vessel at 25 C. A procedure similar in all respects to that described in Example 5 was followed. Well-sized polyester yarns and cellulose ester yarns were obtained.

Example 7.--540 parts of N-methylmethacrylamide and 60 parts of crotonic acid were dissolved in 11,400 parts of oxygen-free water in a closed reaction vessel at 25 C. A procedure similar to that described in Example 5 was followed and well-sized polyester and cellulose ester yarns were obtained.

When similar cellulose acetate yarns were sized under identical conditions with gelatin, Sodium Stymer, and several batches of the sodium salt of the copolymer of 3 9 parts of N-isopropyl acrylamide with 1 part of acrylic acid, the following Duplan values were obtained:

The Duplan Cohesion Tester is a machine designed to test the effectiveness of a slashing solution by testing the cohesion of the sized filament yarn before the warp reaches the loom. Samples of sized yarn under a constant tension are abraded by friction plates moving back and forth on the yarn at a constant rate. The average number of strokes per strand required to separate the filament in ten strands of yarn are reported as the Duplan value. Forty tests on each sample are considered the standard test. In examining the strands at intervals for open places, an air jet is blown along each strand to assist in detecting openings.

The concentration of the sizing solution is limited only by its viscosity, which in turn is determined by the inherent viscosity of the copolymer. A preferred concentration is 5.0% solids of a copolymer having an inherent viscosity of about 3.5, but other concentrations of copolymer of this viscosity can be used, and the inherent viscosity of the copolymer can be varied at any desired concentration between 0.5 and 15.0 viscosity units and even to higher limits if desired. The inherent viscosity of the copolymers can be increased by using lower concentrations of a persulfate-metabisulfite catalyst in making the copolymer, or it can be lowered by using higher concentrations of the catalyst. The nature of the catalyst is not critical.

We claim:

1. The method of sizing textile yarns selected from the group consisting of cellulose acetate yarns and linear polyester yarns, which comprises applying to the yarn an aqueous solution of the sodium salt of the copolymer of 9 parts by weight of N-isopropyl acrylamide and 1 part by weight of acrylic acid, and drying and curing the yarn.

2. The method of sizing textile yarns selected from the group consisting of cellulose acetate yarns and linear polyester yarns, which comprises applying to the yarn a 5% aqueous solution of the sodium salt of the copolymer of 9 parts by weight of N-isopropyl acrylamide and 1 part by weight of acrylic acid, and drying and curing the yarn.

3. A sizing composition for textile yarns selected from the group consisting of cellulose acetate yarns and linear polyester yarns, which consists of an aqueous solution of the sodium salt of the copolymer of 9 parts by weight of N-isopropyl acrylamide and 1 part by weight of acrylic acid.

4. A textile yarn selected from the group consisting of cellulose acetate yarns and linear polyester yarns, carrying a coating of a sizing composition consisting of the sodium salt of the copolymer of 9 parts by weight of N-isoprop'yl acrylamide and 1 part by weight of acrylic acid. J

References Cited in the file of this patent UNITED STATES PATENTS 2,244,703 Hubbuch June 10, 1941 2,807,865 Shippee et al. Oct. 1, 1957 2,816,083 Shearer Dec. 10, 1957 FOREIGN PATENTS 475,671 Great Britain Nov. 24, 1937 

1. THE METHOD OF SIZING TEXTILE YARNS SELECTED FROM THE GROUP CONSISTING OF CELLULOSE ACETATE YARNS AND LINEAR POLYESTER YARNS, WHICH COMPRISES APPLYING TO THE YARN AN AQUEOUS SOLUTION OF THE SODIUM SALT OF THE COPOLYMER OF 9 PARTS BY WEIGHT OF N-ISOPROPYL ACRYLAMIDE AND 1 PART BY WEIGHT OF ACRYLIC ACID, AND DRYING AND CURING THE YARN. 